Heat dissipation module with noise reduction

ABSTRACT

A dissipation device has a dissipation fin set and a centrifugal fan. The centrifugal fan outputs airflow toward the dissipation fin set to remove the heat from it. The centrifugal fan includes a centrifugal impeller mounted on a motor. An outer housing houses the motor and the centrifugal impeller. An inner wall of the housing&#39;s outlet has hair structure to reduce noise. The dissipation fin set includes a fin structure closely attached to a heat source, as well as an airflow channel housing. The airflow channel also includes a hair structure for reducing noise.

RELATED APPLICATIONS

The present application is based on, and claims priority from, Taiwan Application Serial Number 93115561, filed May 31, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Field of Invention

The present invention relates to a heat dissipation module. More particularly, the present invention relates to a heat dissipation module with a noise reduction function.

2. Description of Related Art

As a notebook PC becomes thinner, there isn't enough space for heat convection and heat dissipation design inside the case housing of the notebook PC. When it comes to high-frequency components, such as the CPU (central processing unit) and graphics processing chip, the heat dissipation design hits a bottleneck. Thus, the mainstream framework of heat dissipation design is forced heat convection caused by a centrifugal fan.

FIG. 1 illustrates a perspective view of a conventional centrifugal fan. A centrifugal fan 100 includes a spiral-shaped flow channel design. A centrifugal impeller 103 transforms air dynamic energy into static pressure so as to overcome high flow impedance inside the case housing of the notebook PC. On the other hand, air driven by the centrifugal impeller 103 flows through the spiral-shaped flow channel and generates a wake flow and a vortex, which create high-frequency and narrow-band noise. Airflow 106 accompanied by the noise goes out of an outlet 104 and enters a dissipation fin set, thereby creating even more high-frequency noise due to friction between airflow and an inner wall of the dissipation fin set.

Once heat dissipation efficiency is enhanced, airflow is essentially accelerated. The stronger the airflow is, the more turbulent the wake flow is. Thus, a notebook PC manufacturer faces a challenge between noise and heat dissipation efficiency.

SUMMARY

It is therefore an objective of the present invention to provide a heat dissipation module with a noise reduction function so as to reduce noise caused by strong airflow.

In accordance with the foregoing and other objectives of the present invention, a dissipation device includes a dissipation fin set and a centrifugal fan. The centrifugal fan outputs airflow toward the dissipation fin set to remove the heat from it. The centrifugal fan includes a centrifugal impeller mounted on a motor. An outer housing houses the motor and the centrifugal impeller. An inner wall of the housing's outlet has a hair structure to reduce noise. The dissipation fin set includes a fin structure closely attached to a heat source, as well as an airflow channel housing. The airflow channel also includes a hair structure for reducing noise.

Thus, the dissipation module with noise reduction not only decreases noise amplitudes, but also stabilizes the wake flow. Namely, the airflow with widespread Haystack noise will make a listener feel more comfortable.

It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,

FIG. 1 illustrates a perspective view of a conventional centrifugal fan;

FIG. 2 illustrates a perspective view of a centrifugal fan with a noise reduction function according to one preferred embodiment of this invention;

FIG. 3 illustrates a perspective view of a dissipation module with a noise reduction function according to another preferred embodiment of this invention; and

FIG. 3A illustrates a cross sectional view of a dissipation module with a noise reduction function according to another preferred embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

In order to reduce noise caused by strong airflow, the present invention discloses a heat dissipation module with a noise reduction function. By attaching a hair structure to an inner sidewall of a centrifugal fan's outlet, noise can be reduced. The hair structure can also be attached on an inner sidewall of a flow channel, such as a dissipation fin set, to reduce noise.

FIG. 2 illustrates a perspective view of a centrifugal fan with a noise reduction function according to one preferred embodiment of this invention. A centrifugal fan 200 includes a centrifugal impeller 203. A motor (not illustrated in FIG. 2) in the centrifugal fan 200 rotates the centrifugal impeller 203 to input air from an inlet 202, guide it through a spiral-shaped flow channel 201 and output it via an outlet 204. Because there is friction between airflow 206 and inner sidewall 205 of the spiral-shaped flow channel 201, many specific high frequency and narrow-band noises are created. In order to reduce high-frequency and narrow-band noise, this preferred embodiment attaches a hair structure 222 a on inner sidewall 207 of the outlet 204. The outlet 204 including the hair structure 222 a serves as a noise reduction function, which not only makes the airflow near the sidewall 207 smooth, but also breaks noise caused by airflow 206 hitting the sidewall 207. Moreover, the hair structure 222 a can absorb or interfere with the noise. The hair structure 222 a should be small enough so as not to increase flow impedance. The hair structure 222 a can be attached to the inner sidewall 207 of the outlet 204 by glue.

FIG. 3 illustrates a perspective view of a dissipation module with a noise reduction function according to another preferred embodiment of this invention. FIG. 3A illustrates a cross sectional view taken along the cross-sectional line A-A in FIG. 3. The hair structure 222 a mentioned in FIG. 2 can also be designed in a flow channel 211 of a dissipation fin set 210. This preferred embodiment includes a centrifugal fan 200 and a dissipation fin set 210. Referring to FIG. 3A, the dissipation fin set 210 is closely attached to a heat source 220 to distribute the heat rapidly. The dissipation fin set 210 consists of many fins 212 and airflow channel housing 216. The airflow channel housing 216 includes securing flanges 217 at two sides, and flanges 217 have screw holes for mounting. The dissipation fin set 210 includes an inlet 208 receiving an airflow 206 output by the centrifugal fan 200. The airflow 206 goes through fins 212 and carries the heat out of an outlet 218.

In this preferred embodiment, the hair structure 222 a/222 b is designed both on inner sidewall 207 of the outlet 204 and in the flow channel 211 of the dissipation fin set 210. The outlet including the hair structure has a noise reduction function, which not only makes the airflow near the sidewall smooth, but also breaks noise caused by airflow hitting the sidewall. Moreover, the hair structure can absorb or interfere with the noise. The hair structure, made of Nylon or other artificial fiber, should be small enough so as not to increase flow impedance. The hair structure can be attached to the inner sidewall of the outlet by glue. The hair structure is effective in reducing high-frequency noise, and its cross-sectional area is an important factor. For common design, an inner, cross-sectional diameter D/d is 0.5 to 1.0 times the noise wavelength.

Further, the hair structure doesn't have its hairs arranged uniformly or with the same gaps between hairs. A performance of noise reduction varies as a function of length, density or flexibility of said hair structure.

According to preferred embodiments, the dissipation module with noise reduction not only decreases noise amplitudes, but also stabilizes the wake flow. Namely, the airflow with widespread Haystack noise will make a listener feel more comfortable.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents. 

1. A centrifugal fan with a noise reduction function, comprising: a centrifugal impeller; and an outer housing, said centrifugal impeller being housed inside, said outer housing comprising: an inlet, positioned along an axial direction of said centrifugal impeller; an outlet, positioned along a radial direction of said centrifugal impeller; and a hair structure, positioned on an inner sidewall of said outlet to reduce noise.
 2. The centrifugal fan of claim 1, wherein an inner, cross-sectional diameter of said outlet is about 0.5 to 1.0 times a noise wavelength.
 3. The centrifugal fan of claim 1, wherein said hair structure is made of Nylon or artificial fiber.
 4. The centrifugal fan of claim 1, wherein said hair structure is attached to said inner sidewall of said outlet by glue.
 5. The centrifugal fan of claim 1, wherein a performance of noise reduction varies as a function of length, density or flexibility of said hair structure.
 6. A heat dissipation module with a noise reduction function, comprising: a dissipation fin set, closely attached to a heat source; a airflow channel housing, securing said dissipation fin set and the heat source inside, wherein said airflow channel housing includes a first inlet, a first outlet and a first hair structure, positioned on a inner sidewall of said airflow channel housing to reduce noise; and an outer housing, a centrifugal impeller being housed inside, said outer housing comprising: a second inlet, positioned along an axial direction of said centrifugal impeller; a second outlet, positioned along a radial direction of said centrifugal impeller, wherein air driven by said centrifugal impeller is guided out of said second outlet and guided into said first inlet; and a second hair structure, positioned on a inner sidewall of said second outlet to reduce noise.
 7. The heat dissipation module of claim 6, wherein an inner, cross-sectional diameter of said second outlet is about 0.5 to 1.0 times a noise wavelength.
 8. The heat dissipation module of claim 6, wherein an inner, cross-sectional diameter of said airflow channel housing is about 0.5 to 1.0 times a noise wavelength.
 9. The heat dissipation module of claim 6, wherein said first and second hair structures are made of Nylon or artificial fiber.
 10. The heat dissipation module of claim 6, wherein said first hair structure is attached to said inner sidewall of said airflow channel housing by glue.
 11. The heat dissipation module of claim 6, wherein said second hair structure is attached to said inner sidewall of said second outlet by glue.
 12. The heat dissipation module of claim 6, wherein a performance of noise reduction varies as a function of length, density or flexibility of said first hair structure.
 13. The heat dissipation module of claim 6, wherein a performance of noise reduction varies as a function of length, density or flexibility of said second hair structure. 